Tertiary ammonium ion induces contraction of rat aorta segments and increases the mobility of lipids in the membrane of rat aorta smooth muscle cells.
The effects of tertiary ammonium ion--IEM-1194 (decyldiisopropylammonium bromide)--on smooth muscle cells (SMC) isolated from rat aorta were investigated. Using the patch-clamp technique in the cell-attached configuration, two types of effects on the Ca(2+)-activated K+ channels were recorded after application of IEM-1194: an increase in the number of fast transition bursts in open channels and the prolongation of the burst. The removal of the agonist led to the activation of these channels. Mechanical responses of aortic rings were recorded using the method of isometric tension measurements. IEM-1194 (100-400 microM) caused contractions consisting of two phases. The first phase emerged immediately after application of the agonist. The second phase was observed 10-15 min after application. The contraction of the aorta was followed by the relaxation for over 1.5 h. The same results were obtained in the Ca(2+)-free external solution. Measurements of SMC membrane fluidity by the EPR method showed that IEM-1194 induced an increase in the mobility of membrane lipids. Based on these results, we suggest a mechanism of IEM-1194 action on the Ca(2+)-activated K+ channels.
Shipachev
V V
VV
Institute of Experimental Cardiology, Russian Cardiology Research Center, Moscow, Russia.
Timoshin
A A
AA
Gmiro
V E
VE
Gusev
A S
AS
Savina
M V
MV
Serebryakov
V N
VN
D000818:Animals; D001011:Aorta; D066298:In Vitro Techniques; D007477:Ions; D007537:Isometric Contraction / Q000187:drug effects*; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D011437:Propylamines / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D007477:Ions; D008563:Membrane Lipids; D026902:Potassium Channel Blockers; D011437:Propylamines; D000644:Quaternary Ammonium Compounds; C060661:N-decyl-N,N-diisopropylamine